The present invention relates generally to a radio apparatus.
The invention is based on a radio apparatus as generically defined by the preamble to the main claim.
From the publication entitled xe2x80x9cEuropean Digital Cellular Telecommunications System (Phase 2); Radio Transmission and Reception (GSM 05.05)xe2x80x9d of the European Telecommunications Standard Institute (ETSI) of May 1994, specifications for mobile radio transmission and reception are known. A plurality of power stages are provided, such as a power stage 2 with a maximum output power of 8 W and a power stage 4 with a maximum power of 2 W. The power requirements made of the mobile radio apparatuses pertain to the antenna output of the applicable mobile radio apparatus.
From U.S. Pat. No. 5,303,395, a system for controlling the power stage of high-frequency (HF) signals that are output by a portable radio apparatus is known. The portable radio apparatus includes a first power supply, a first amplifier stage, and a microcomputer that is connected to the first amplifier stage in order to select from a plurality of power stages. An indicator signals when the radio apparatus is connected to a motor vehicle power supply. In response, the microcomputer generates a control signal, which is representative for the desired power stage. A second amplifier stage is connected to the first amplifier stage and receives HF signals that are at the first power stage. An amplifier control circuit is connected to the second amplifier stage and receives the control signal. It responds by setting the gain of the second amplifier stage to one of at least two constant gain values, so that the HF signals output at the desired power stages are made available.
From European Patent Disclosure EP 0 602 608 A1 a mobile radio apparatus is known that comprises a portable unit and a stationary part and that is provided for control between two apparatuses, each with its own control unit. By way of the control unit, a transmission power regulation is performed in the booster, and the booster is turned on and off from the portable apparatus. In the opposite direction, the portable apparatus receives information as to the presence or absence of a booster. The control signals needed in the booster are limited to two, namely the signal for switching over the amplification and the signal for turning all the power consumers on and off, except for the circuit that has to assure the control function between the booster and the hand-held apparatus in the standby mode.
The radio apparatus of the invention has the advantage over the prior art that the radio apparatus can be operated at various power stages and can thus be used flexibly. A further advantage is that an inexpensive radio apparatus with a lower power stage can easily be equipped for operation at a higher power stage by means of a connectable HF amplifier circuit. Thus using the appropriate accessory equipment, a single radio apparatus can be used for various power stages, making for an overall cost saving since only the applicable HF amplifier circuit has to be produced or purchased as an accessory, and not a complete new radio apparatus.
It is also advantageous that the range of a radio apparatus.
By means of the provisions recited in the dependent claims, advantageous refinements of and improvements to the radio apparatus defined by the main claim are possible.
It is especially advantageous to use an evaluation circuit and to detect a HF amplifier circuit connected to the radio apparatus by means of the evaluation circuit. This provides a simple opportunity of ascertaining the current power stage of the radio apparatus.
It is also advantageous that the radio apparatus has an input to which one output of the HF amplifier circuit can be connected; that the evaluation circuit is connected to the input; and that the evaluation circuit triggers the transmitter unit of the radio apparatus as a function of signals or the voltage drop at the input. In this way, a HF amplifier circuit connected to the radio apparatus can be detected especially simply and reliably, and the radio apparatus can be logged in in a simple way in accordance with its current power stage in the radio network. It is especially advantageous that the evaluation circuit is connected to the antenna output, and if the evaluation circuit triggers the transmitter unit of the radio apparatus as a function of signals or of the voltage drop at the antenna output. This affords an especially simple and reliable opportunity of detecting the connection of a corresponding HF amplifier circuit to the radio apparatus and to have the radio apparatus logged in in accordance with its current power stage in the radio network; no additional connecting line between the radio apparatus and the HF amplifier circuit is needed for detecting the connection of the HF amplifier circuit to the radio apparatus.